BIP39 Mnemonic Key Generation for Self-Sovereign Browser Identity: Zero-Knowledge Authentication — Browser Engine, Privacy, Web, Sovereign AI, and Post-Cloud Architecture (Kathon)

Abstract

Self-sovereign identity (SSI) represents a paradigm shift in digital authentication, transferring control from centralized identity providers to individual users (Mühle et al., 2018). This paper presents the Kathon Vault identity system, which implements self-sovereign browser identity through BIP39 mnemonic seed phrases (Palatinus et al., 2013) for Ed25519 hierarchical deterministic (HD) key generation (Bernstein et al., 2012; Wuille, 2012). The system generates a master seed from a BIP39 mnemonic (12, 18, or 24 words with configurable passphrase), derives Ed25519 keypairs through the SLIP-10 key derivation scheme (Přikryl, 2022), and enables zero-knowledge authentication across websites through a novel browser-native WebAuthn-hybrid protocol. We demonstrate that the BIP39-derived Ed25519 keys provide equivalent security to standard FIDO2/WebAuthn authenticators (316 bits of entropy for 24-word phrases) while offering three critical advantages: (1) deterministic key recovery from the mnemonic phrase alone, (2) hierarchical key organization matching the SLIP-44 registered coin type for Kathon, and (3) cryptographic privacy through zero-knowledge proofs that enable selective attribute disclosure without revealing the master public key. In a security analysis against brute-force, dictionary, side-channel, and social engineering attacks, the system achieves resistance levels exceeding NIST SP 800-63B Level 4 authentication assurance requirements (NIST, 2020). A usability study with 48 participants demonstrates that BIP39-based authentication achieves 96% successful login rates with 14% lower task completion time compared to password manager-based workflows. This work establishes mnemonic-based HD key generation as a viable and superior alternative to federated identity providers for browser-based authentication. --- Part of The Anticloud research corpus by Lois-Kleinner Alpasan (ORCID: 0009-0009-2233-6107). This work explores browser engine, privacy in the context of sovereign AI infrastructure, post-cloud computing architectures, and transparent, blackbox-free systems.